1. Field of the Invention
The present invention relates to an engine device for motorcycles.
2. Description of Related Art
An engine device for motorcycles has been conventionally provided with a motor type starting device for starting an engine. The motor type starting device transmits drive force of the starter motor, for example, to a crankshaft through a reduction gear train housed in a side space within the crankcase (See Japanese Patent Document JP-A-Hei 6-341327, for example).
Such a reduction gear train is made up of a plurality of transmission gears each supported for rotation on a plurality of the respective support shafts disposed parallel to a motor shaft of the starter motor and the crankshaft.
Sometimes, however, a generator, which is usually provided integrally for rotation at the end of a crankshaft, is provided integrally for rotation at the end of a generator shaft disposed parallel to and offset from the crankshaft, depending on the layout of the vehicle body.
Therefore, some of transmission gears of the reduction gear train in the motor type starting device are configured such that they are supported on the generator shaft, but such a transmission gear is required to have an outside diameter greater than that of the rotor of the generator having a relatively large diameter.
Thus, the starter motor, which transmits drive force to the crankshaft through a reduction gear train having a relatively large outside diameter, is disposed at the upper part of the crankcase distant from the crankshaft. The starter motor has a strong influence on the weight balance of the vehicle in the longitudinal or the lateral direction because of its heavy weight and might cause a deviation of the weight balance because of its disposition distant from the crankshaft.
In addition, in the case where a V-type engine is provided with a motor type starting device, the starter motor can be disposed forward of the engine only at the upper part of the crankcase. In this case, the starter motor which is disposed away from the crankshaft, is disposed further forward of a cylinder block of the engine, and a running wind hitting against cooling fins might be blocked in an air-cooled engine.